textproduct: Albany

WHAT HAS CHANGED

Confidence in a brief period of rain quickly changing to wet snow this afternoon has increased as the main cold front rapidly sweeps through the region and temperatures plummet. Wet snowfall amounts now range 1 to 3 inches in the Rensselaer Plateau and the southern Greens with even coating to 0.5" in the Capital District, the Taconics and western MA. Wet snow and the potential for wet surfaces to turn icy as temperatures rapidly drop can lead to slippery travel for the P.M commute.

KEY MESSAGES

1) Slippery travel today in the southwest Adirondacks between accumulating wet snow through this morning followed by rapidly falling temperatures that will allow any wet surfaces to become icy. Additional lake effect snow showers tonight combined with gusty winds can result in continued hazardous travel.

2) Wet surfaces across eastern NY and western New England can quickly turn icy this afternoon (including the P.M commute) as temperatures rapidly fall into the 20s. There is even a 20 to 50% chance for at least 1 inch of snow in the southern Greens and Rensselaer Plateau.

3) We continue to monitor a few disturbance for the weekend that may bring additional light snow accumulations. However, significant impacts are not expected.

DISCUSSION

KEY MESSAGE 1...

Latest water vapor imagery overlaid with RAP pressure analysis continues to show our now closed parent cyclone positioned well to our west with a north to south oriented baroclinic zone near the I-81 corridor based on the direction of the sfc winds. Southerly flow ahead and along the boundary continues to aid in moisture transport with warm air advection supporting patchy light rain showers in valley areas with areas of snow showers in the southwest Adirondacks due to upslope flow. With much of eastern NY and western New England still in the warm/moist sector ahead of the front, temperatures remain mild in the 30s and 40s with foggy conditions in place. As a secondary low develops along the boundary early this morning, snow should become more widespread and steadier in the southwest Adirondacks leading to more appreciable wet snow accumulations. Then, as the front marches eastward in this area by 15 - 18 UTC, we should see a period of moderate snow as temperatures rapidly fall into the teens and 20s. Between the additional 1 to 3 inches of wet snow and rapidly falling temperatures, any wet surface can easily turn icy leading to slippery travel through the day today.

While the steady snow turns lighter and even stops for a period in the southwest Adirondacks this afternoon, cold air advection will kick into high gear this evening as westerly winds strengthen resulting in lake effect snow showers. The initial lake effect bands extend into the southwest Adirondacks this evening and continue overnight. Inversion heights initially will be rather high near 800hPa this evening supporting steady lake effect snow but forecast soundings show inversion heights decreasing after 06 UTC indicating bands weaken. An additional 1 to 2 inches of snow is expected overnight. Westerly winds also become gusty reaching 25 to 30mph tonight which when combined with falling snow can reduce visibility.

KEY MESSAGE 2...

While most of eastern NY and western New England starts the day mild, temperatures will rapidly fall from west to east midday into this afternoon as the main cold front marches eastward and secondary low intensifies. High resolution guidance even shows a period of steady precipitation occurring as the front pushes through the region and with temperatures crashing, expecting rain to mix with or even changeover to a period of wet snow (especially in higher elevations). Latest probabilistic guidance shows a 10 to 40% chance for at least 0.1" of snow falling in the Mohawk Valley into the Upper Hudson Valley, southern Vermont and northern Taconics. There is even a 10 to 30% chance for at least a 0.5" of wet snow in the Upper Hudson Valley, the northern Taconics and southern Greens this afternoon as the main front arrives. Our latest forecast reflects a slight increase in snow accumulations in these areas with amounts ranging from a coating up to 2 inches. We even show coating to a few tenths in the Capital District but this will be dependent on precipitation intensity. Should precip fall heavy enough as the front sweeps through and temperatures plummet, there may be a quick changeover to wet snow. Higher confidence in wet snow accumulations early to mid afternoon today looks to be in the Upper Hudson Valley, northern Taconics, and southern VT where there looks to be more of an overlap of falling temperatures coincident with heavy precipitation rates.

Once the cold front marches through by early to mid afternoon, temperatures rapidly fall into the 20s (teens in the high terrain) and any wet surfaces can easily turn icy. This unfortunately can continue into the afternoon commute so be careful on your way home from work/school. Winds will also turn gusty reaching 25 to 35mph which will help dry out surfaces but given how quickly temperatures plummet, there may not be enough drying time.

It will turn quite cold tonight with many falling into the single digits and teens across eastern NY and western New England as strong cold air advection continues. West to northwest winds remain breezy overnight as the true punch of cold air races eastward which should help dry out surfaces.

KEY MESSAGE 3...

Broad troughing over Eastern Canada extends into the Eastern CONUS this weekend, keeping an unsettled pattern in place. Weak warm air advection remains focused along a lingering northeast to southwest baroclinic zone on Saturday which supports periods of rain and snow showers. As this combines with additional weak forcing for ascent from an incoming shortwave that becomes sheared out, rain and snow showers may become more widespread. However, overall precip intensity looks mainly light and with temperatures warming above freezing in the afternoon, overall impacts look minimal. Best chance for any slippery travel looks to be in the morning when colder temperatures are still in place.

Heading into Sunday, we continue to closely monitor a more potent shortwave rounding the base of our broad troughing which will allow it to amplify into the Southeast and potentially induce cyclogensis off the East Coast. Latest ensemble clusters show two main scenarios. Should a stronger trough develop in response to phasing with the incoming shortwave, then the resulting coastal low may take a slightly further west track and therefore allow the northwest fringe of its precipitation shield to brush the Northeast. On the other hand, if the resulting trough is a bit weaker, the coastal low looks to track further out to sea with little impacts in eastern NY and western New England on Sunday. Our latest forecast shows slight to chance POPs on Sunday given that ~60% of the ensembles lean on the further east solution but we will continue to monitor trends. The ~40% of the ensembles that show a further west track also show increased precipitation amounts focused mainly in areas near and south/east of I-90. This indicates that even if the coastal low tracks west, there is a low chance for widespread impacts.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Through 12z/Fri...Widespread IFR/MVFR conditions will likely continue for most of this morning as a low pressure system continues to slowly move across the region. TEMPO groups have been included to note fluctuation in flight conditions. KPOU may only lower to MVFR at times this morning. A gradual return to VFR conditions is expected by or shortly after 18z/Thu as a cold front crosses. A few snow showers could bring a return to IFR/MVFR conditions after 18z/Thu with the higher confidence at this time at KALB/KPSF where a PROB30 group was included between 21z/Thu and 02z/Fri.

Wind will become south to southwesterly early this morning then become west to southwesterly after 18z/Thu and west to northwesterly after 00z/Fri with speeds increasing to 10-15 kt with gusts 20-30 kt.

Outlook...

Friday Night: Low Operational Impact. Chance of SHSN. Saturday: Moderate Operational Impact. Chance of SHSN...SN. Saturday Night: Low Operational Impact. Slight Chance of SN. Sunday: Moderate Operational Impact. Chance of SN. Sunday Night: No Operational Impact. NO SIG WX. Martin Luther King Jr Day: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Low Operational Impact. Breezy. Slight Chance of SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Winter Weather Advisory until 7 PM EST this evening for NYZ032- 033. MA...None. VT...None.